I've setup the system for a bed and breakfast.

when i reserve some date, a pop up window shows me the reserved dates with the total amount on it which is perfect, but when i save and checkout, the amount is now 0.

After confirming the reservation ....... in the reservation tab in the backend ....... the total is 0

I want to buy the component but this has to be ok before !

regards

Hello, according your description I don't know what is wrong.
I have only one idea: reservation items are saved into Joomla sessions.
There is maybe something wrong with sessions.
Try control settings of Joomla sessions storage.
The best setting is database storage.